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Preksha Dhyanat
iron increases greatly during pregnancy. Each haemoglobin has four iron atoms which combine loosely with four molecules of oxygen in the lungs. There are about 280 million molecules packed into each of the 5 million red blood cells in each cubic millimetre of blood. Contents of haemoglobin in the blood is an index of health.
White Blood Cells (Leukocytes). These are essentially colourless, as they do not contain haemoglobin. They are larger than red cells. They are not uniform in size, shape and appearance. Unlike sed cells which are carried passively along in the blood-flow, white cells move actively. "The main functions of most of the white cells are performed outside the actual blood, in the neighbourhood of tissues. These soldiers of the body are second-line defenders, (skin and mucous membranes are the first line), against foreign invaders ready to fight to death, if need be. Red cells outnumber the white cells by about 700 to 1. The life-span of a white cell is extremely variable. It may be only a few hours, or with luck may be measured in months. On the whole, the life of the white cell is harder than that of the red cell. It is likely to meet an untimely death in the service of the body. A continuous production of new white cells is, therefore, essential. The red bone-marrow is also the site of the formation of the leukocytes. Some others are produced in the various lymph nodes, the spleen, the thymus gland and the tonsils. Platelets (Thrombocytes)
They are also called clotting cells (thrombo means clot). They are more numerous than white cells, but less so than red cells. They live in the blood for five to eight days after which they are destroyed in the spleen and other organs. They are a key link in the mechanisms for the prevention of blood loss and they go into action when a Blood-vessel is cut or pierced and blood is being lost. A substance called platelet factor initiates a chain of chemical Teactions leading to the formation of a clot which effectively plugs the cut or hole. Blood-clotting is a complicated chain of chemical reactions involving 13 separate factors. 1. The normal level of haemoglobin in the blood is 13.0 to 18.0 Srams/100 ml for men and 12.0 to 16.0 grams/100 ml for women,
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